Any parent will know that adolescence is a fraught period for their children.

They want privacy and time alone. They complain that parents prevent them from doing things independently.

What more a stepchild, who has always struggled with doubts about being part of a family with customs and practices that are alien - even anathema - to him?

This Sunday, Hong Kong marks the 15th year of its return to the motherland with an elaborate line-up of celebrations.

The mysteries of the Qianlong Emperor's private Forbidden City garden were revealed for the first time in an exhibition last week. People's Liberation Army parachuters will bedazzle the crowds on Sunday morning, with fireworks wreathed to form the words 'HK 15' capping the performance at night.

But the biggest headliner is Chinese President Hu Jintao.

He will arrive from the capital tomorrow, bearing gifts said to be hefty. Word is that he will announce major initiatives to hitch Hong Kong's economic caboose more firmly to the Chinese locomotive.

But casting a pall over the celebrations is simply this: tetchy Hong Kongers are not much in a mood to toast the 15th anniversary of their city's handover from British colonial rule to Chinese sovereignty.

One long and present shadow is the suspicious death of Tiananmen Square activist Li Wangyang. His body was found in a hospital in Hunan on June 6 - just days after he vowed to press on with the fight for democracy - with a noose around his neck. The Chinese authorities ruled it a suicide; his family and supporters cried murder.

The case stirred outrage in Hong Kong, with 25,000 people marching to Beijing's Liaison Office two Sundays ago, forcing the Hunan authorities to accede to an investigation.

And a drive to collect 100,000 signatures for a petition to present to Hu is underway.

Li's death particularly resonates with Hong Kongers as it embodies their fears that Beijing will undermine their own fiercely- guarded values of freedom, human rights and the rule of law.

There is also deep unhappiness over its interference - covert or otherwise - in various local elections, most recently, the March ballot for the chief executive.

Such cases poison the relationship between Hong Kong and China. As some Hong Kongers put it: they embrace the motherland, but not the excesses of its guardians, the communist regime.

But the overall picture of the China-Hong Kong relationship is more complicated than that.

Even before Wang's death, relations had already sunk to a low. A Hong Kong University survey last month, part of a series since 1997, found that 32 per cent of Hong Kongers view the central government negatively - a record nadir. Other indicators - trust in Beijing, confidence in the One Country, Two Systems framework - drew similar results.

But the negativity is towards not just the communist regime. The survey showed that more Hong Kongers dislike - than like - the people from China, the only country besides the Philippines (where eight Hong Kong tourists were killed in a hijack in 2010) with that dubious distinction.

The decline started about four years ago, say observers. As China watcher Michael Yahuda of the London School of Economics and Political Science notes, Hong Kongers "seemed happier with the first 10 years than the last five".

It is perhaps no coincidence that the recent years coincided with the rise of China as an emerging superpower - a historic event that has dimmed the lustre of the Pearl of the Orient.

Previously, China needed Hong Kong more, now it is Hong Kong that needs China more. The latter has become the largest external investor here, contributing 36 per cent of total direct investment. Its companies are key players in the stock exchange, accounting for 60 per cent of market capitalisation.

Meanwhile, mainlanders visit in droves with their chequebooks, snapping up items from Gucci bags to luxury apartments.

And so, the Chinese wonder why Hong Kongers are not more grateful. But it is difficult to be so when one is used to being the superior one, who hated the neighbouring family's ways - the autocratic father who rules with an iron fist and his hillbilly offspring who spit and litter in public.

Back in its fold, Hong Kong is dependent on the father for its allowance. This creates existential angst that has only grown as the disparity increases. As taxi driver Lai Chung Ming puts it, wo men xin li bu ping heng - they are afflicted by disequilibrum.

This was a problem that was held somewhat at bay in the first decade, as pragmatic Hong Kongers focused on trying to reap the benefits from the relationship.

But over the past few years, not enough of the growth generated has trickled down to the masses. Hong Kong's rich such as the property tycoons have benefited from the influx of Chinese money. But ordinary Hong Kongers see the flipside - rising inflation, spiralling housing prices and inadequate hospital beds.

Meanwhile, the Hong Kong government has not engaged its people on the challenges from growing integration with the mainland, as its focus had been on the pro-Beijing, business and professional elites, says Hong Kong University's Professor Peter Cheung.

Yet, the fact remains that much is at stake for both sides to make this relationship work.

China still needs Hong Kong to carry out crucial financial transactions, given its own relatively closed system. The latter's expertise in commercial law too remains useful.

There is also the matter of face. As Professor Yahuda notes, given the fears in East Asia of an overbearing nationalistic China that does not play by the rules, Beijing cannot afford to reinforce that image by heavy-handed interference in Hong Kong's affairs; that would mean tearing up its own rule book - the One Country, Two Systems formula that grants Hong Kong autonomy and the preservation of its capitalist and political identity for 50 years.

Last, but hardly least, a nervy China that is fighting fires on different fronts - from internal party politics to village protests - simply does not need a rebellious Hong Kong to add to its problems.

With China's long-term trajectory as yet an unknown, Hong Kong plays an important role as 'an experiment in Chinese federalism', says Prof Cheung, one that could portend a more democratic China by accommodating institutional and ideological pluralism - so long as it does not hurt Beijing's core interests like national unity and stability.

Hong Kong has also imparted some governance lessons to China. Its officials, for instance, have been appointed to advise on banking reforms. In fighting graft, Beijing told Shenzhen officials to study Hong Kong's Independent Commission Against Corruption.

Allowing Hong Kong to play such roles will not just help China in its reforms, but also improve the dynamics of the relationship.

Adolescence is a difficult period. The good news is that most get through it - especially those with parents who earn their children's respect and are vigilant to their needs.